I have a scheduled instance running in the background (task scheduler).
Things were working fine. I have been observing this since a week.
When I stop the scheduled instance and run wptdriver.exe in the foreground, it picks up the test and runs, but shows a longer delay.
Also shows 'your profile doesn't exist'
version 2.15.0.183

WPT generally doesn't support running in the background. Do you have the task configured to only run when a user is logged in and at the time of login (and using the account of the user that you have configured to autologon)?

Just wondering if its a Chrome or Windows OS (task scheduler - background job vs foreground) issue? Earlier the same combination worked all OK...only some unknown change somewhere (like security patching for OS and browsers etc) could have resulted into current status?

Chrome browser ver. shows Version 38.0.2125.111 m
while looking for chrome version info it autoupgraded to Version 38.0.2125.122 m.

also curious on that point i.e....should autoupgrade of chrome browser version cause any issues? Want to know recommendations on that as well on chrome pop-ups like "your profile could not be opened properly"